Method and apparatus for multiple phase splitting for dual band IQ subharmonic mixer drive chains

Abstract

A method and apparatus are provided for generating first and second modulation signals from a local oscillator signal for quadrature subharmonic modulation of a quadrature amplitude modulated information signal. The method includes the steps of delaying the local oscillator signal in a plurality of incremental odd and even delay steps to form respective sets of odd and even modulator signals, said odd set of modulator signals together forming the first modulation signal and said even set forming the second modulation signal for quadrature subharmonic modulation of the quadrature amplitude modulated information signal and controlling a magnitude of the incremental delays based upon a predetermined phase offset between the local oscillator signal and a last delay step of the incremental delay steps.

1. A method of generating at least two modulation signals from a local oscillator signal for quadrature subharmonic modulation of a quadrature amplitude modulated information signal, such method comprising the steps of:
 delaying the local oscillator signal in a plurality of incremental delay steps to form at least two sets of modulator signals, one of said sets of modulator signals together forming the first modulation signal and another of said sets forming the second modulation signal for quadrature subharmonic modulation of the quadrature amplitude modulated information signal; and 
 controlling a magnitude of the incremental delays based upon a predetermined phase offset between the local oscillator signal and a last delay step of the incremental delay steps. 
 
   
   
     2. The method of generating first and second local oscillator signals as in  claim 1  further comprising defining the first modulation signal as a real part of the quadrature subharmonic modulation signal. 
   
   
     3. The method of generating first and second local oscillator signals as in  claim 1  further comprising defining the second modulation signal as an imaginary part of the quadrature subharmonic modulation signal. 
   
   
     4. The method of generating first and second local oscillator signals as in  claim 1  further comprising defining the delay of each delay step as substantially equal to ninety degrees divided by a modulator multiplier value. 
   
   
     5. The method of generating first and second local oscillator signals as in  claim 4  further comprising defining the first and second modulation signals as having a number of respective odd and even members equal to two times the modulator multiplier value. 
   
   
     6. The method of generating first and second local oscillator signals as in  claim 1  further comprising defining a first incremental delay step as equal to zero degrees. 
   
   
     7. The method of generating first and second local oscillator signals as in  claim 6  further comprising defining a second incremental delay step as equal to forty-five degrees. 
   
   
     8. The method of generating first and second local oscillator signals as in  claim 7  further comprising defining a third incremental odd delay step as equal to ninety degrees. 
   
   
     9. The method of generating first and second local oscillator signals as in  claim 8  further comprising defining a fourth incremental delay step as equal to one-hundred and thirty-five degrees. 
   
   
     10. Apparatus for generating at least two modulation signals from a local oscillator signal for quadrature subharmonic modulation of a quadrature amplitude modulated information signal, such apparatus comprising:
 means for delaying the local oscillator signal in a plurality of incremental delay steps to form at least two sets of modulator signals, one of said sets of modulator signals together forming the first modulation signal and another of said sets forming the second modulation signal for quadrature subharmonic modulation of the quadrature amplitude modulated information signal; and 
 means for controlling a magnitude of the incremental delays based upon a predetermined phase offset between the local oscillator signal and a last delay step of the incremental delay steps. 
 
   
   
     11. The apparatus for generating first and second local oscillator signals as in  claim 10  further comprising means for defining the first modulation signal as a real part of the quadrature subharmonic modulation signal. 
   
   
     12. The apparatus for generating first and second local oscillator signals as in  claim 10  further comprising means for defining the second modulation signal as an imaginary part of the quadrature subharmonic modulation signal. 
   
   
     13. The apparatus for generating first and second local oscillator signals as in  claim 10  further comprising means for defining the delay of each delay step as substantially equal to ninety degrees divided by a modulator multiplier value. 
   
   
     14. The apparatus for generating first and second local oscillator signals as in  claim 13  further comprising means for defining the first and second modulation signals as having a number of respective odd and even members equal to two times the modulator multiplier value. 
   
   
     15. The apparatus for generating first and second local oscillator signals as in  claim 10  further comprising means for defining a first incremental delay step as equal to zero degrees. 
   
   
     16. The apparatus for generating first and second local oscillator signals as in  claim 15  further comprising means for defining a second incremental delay step as equal to forty-five degrees. 
   
   
     17. The apparatus for generating first and second local oscillator signals as in  claim 16  further comprising means for defining a third incremental delay step as equal to ninety degrees. 
   
   
     18. The apparatus for generating first and second local oscillator signals as in  claim 17  further comprising means for defining a fourth incremental delay step as equal to one-hundred and thirty-five degrees. 
   
   
     19. Apparatus for generating first and second modulation signals from a local oscillator signal for quadrature subharmonic modulation of a quadrature amplitude modulated information signal, such apparatus comprising:
 a delay chain adapted to delay the local oscillator signal in a plurality of incremental delay steps to form at least two sets of modulator signals, one of said sets of modulator signals together forming the first modulation signal and another of said sets forming the second modulation signal for quadrature subharmonic modulation of the quadrature amplitude modulated information signal; and 
 a feedback circuit adapted to control a magnitude of the incremental delays based upon a predetermined phase offset between the local oscillator signal and a last delay step of the incremental delay steps. 
 
   
   
     20. The apparatus for generating first and second local oscillator signals as in  claim 19  wherein the first modulation signal further comprises a real part of the quadrature subharmonic modulation signal. 
   
   
     21. The apparatus for generating first and second local oscillator signals as in  claim 19  wherein the second modulation signal further comprises an imaginary part of the quadrature subharmonic modulation signal. 
   
   
     22. The apparatus for generating first and second local oscillator signals as in  claim 19  wherein the delay chain further comprises a plurality of series connected delay elements where each delay step is substantially equal to ninety degrees divided by a modulator multiplier value. 
   
   
     23. The apparatus for generating first and second local oscillator signals as in  claim 22  wherein the first and second signals further comprise respective sets of odd and even members equal to two times the modulator multiplier value. 
   
   
     24. The apparatus for generating first and second local oscillator signals as in  claim 19 , wherein a first incremental odd delay step of the delay chain further comprises zero degrees. 
   
   
     25. The apparatus for generating first and second local oscillator signals as in  claim 24  wherein a second incremental delay step further comprises forty-five degrees. 
   
   
     26. The apparatus for generating first and second local oscillator signals as in  claim 25  wherein a third incremental delay step further comprises a total delay of ninety degrees. 
   
   
     27. The apparatus for generating first and second local oscillator signals as in  claim 26  wherein a fourth incremental delay step further comprises a total delay of one-hundred and thirty-five degrees. 
   
   
     28. A method of providing first and delayed second modulator signals for modulation of a quadrature amplitude modulated signal, such method comprising the steps of:
 detecting a phase difference relating the first and second modulator signals; 
 filtering the detected phase difference; and 
 adjusting the phase difference between the first and second modulator signal based upon the filtered, detected phase difference to a phase difference value equal to ninety degrees divided by a modulator multiplier value for quadrature subharmonic modulation of the quadrature amplitude modulated signal.